Dummy bottom electrode in interconnect to reduce cmp dishing

ABSTRACT

The present disclosure relates an integrated circuit (IC). A plurality of metal layers is disposed within an inter-layer dielectric (ILD) material over the substrate. A memory cell is disposed over a first metal layer at a memory region and comprising a bottom electrode directly above a first metal line within the first metal layer and a top electrode separated from the bottom electrode by a resistance switching element. A dummy structure comprises a dummy bottom electrode arranged directly above a second metal line within the first metal layer at a logic region adjacent to the memory region.

CROSS REFERENCE TO RELATED APPLICATION

This application is a Continuation of U.S. patent application Ser. No.14/810,763 filed on Jul. 28, 2015 in the name of Harry-Hak-Lay Chuang,et al., which is entitled “Dummy Bottom Electrode in Interconnect toReduce CMP Dishing” and is hereby incorporated in its entirety.

BACKGROUND

Many modern electronic devices contain electronic memory configured tostore data. Electronic memory may be volatile memory or non-volatilememory. Non-volatile memory is able to store data in the absence ofpower, whereas volatile memory is not. Magnetoresistive random-accessmemory (MRAM) and resistive random access memory (RRAM) are promisingcandidates for next generation non-volatile memory technology due torelative simple structures and their compatibility with complementarymetal-oxide-semiconductor (CMOS) logic fabrication processes. As thesize of on-chip components is scaled (i.e., reduced), device “shrinkage”allows engineers to integrate more components and more correspondingfunctionality onto newer generations of ICs. In recent technology nodes,this has allowed for non-volatile memory to be integrated on anintegrated chip with logic devices.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 illustrates a cross-sectional view of some embodiments of anintegrated circuit (IC) having a memory region and an adjacent logicregion.

FIG. 2 illustrate a cross-sectional view of some other embodiments of anintegrated circuit (IC) having a memory region and an adjacent logicregion.

FIG. 3 illustrates a flow diagram of some embodiments of a method ofmanufacturing an integrated circuit (IC).

FIGS. 4-12 illustrate cross-sectional views of some embodiments showinga method of manufacturing an integrated circuit (IC).

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

A trend in semiconductor manufacturing is to integrate different typesof devices on a single substrate to achieve higher integration. Oneexample is a substrate having a logic region, in which logic devices areformed, and a memory region, in which magnetic random access memory(MRAM) or resistive random access memory (RRAM) devices are formed. Toform these memory cells, which are formed in an interconnect structureoverlying the substrate, a bottom electrode layer can be formed in theinterconnect structure and over the memory region, and chemicalmechanical polishing (CMP) can be used to planarize the bottom electrodelayer. In such manufacturing processes, however, chemical mechanicalpolishing (CMP) may not result in a planar surface over the entiresubstrate. For example, when the bottom electrode layer (which has arelatively high structural integrity and tends to “resist” CMPrelatively well) is present over the memory region but does not extendover the logic region, a metal interconnect line (which has a relativelylow structural integrity compared to the bottom electrode layer) may beexposed to CMP in the logic region. Because this metal interconnect lineis structurally “weaker” than the bottom electrode, performing CMP onthe bottom electrode layer can cause “dishing” of the metal interconnectlines in the logic region. Therefore, after bottom electrodeplanarization for the memory devices, portions of the metal interconnectlines in the logic region can end up being thinner than in the memoryregion, possibly even being removed. Consequently, these eroded metallines can degrade the reliability of the resultant IC.

Accordingly, the present disclosure relates to integrated circuit (IC)techniques to protect metal lines in such logic regions. Approachesinclude adding dummy structures directly above metal lines in the logicregion to act as a CMP stop, thereby preventing CMP dishing of the metallines when a bottom electrode of a memory cell is planarized. A dummystructure can comprise a dummy bottom electrode which corresponds inmany regards to a bottom electrode of the memory cell but which isdisposed over the logic region rather than over the memory region. Thedummy bottom electrode is configured to protect underlying lower metallines in the logic region from dishing during planarization of thebottom electrode layer, and thus results in more uniform metal linesover the IC.

FIG. 1 shows a cross-sectional view of an integrated circuit (IC) 100disposed over a substrate 101 according to some embodiments.

As shown in FIG. 1, the IC 100 includes substrate 101 and aninterconnect structure 105 over the substrate 101, which are splitbetween a memory region 124 and an adjacent logic region 126. The memoryregion 124 can correspond to an array of memory cells (e.g., memory cell130), which are disposed in the interconnect structure 105, while thelogic region 126 can couple logic devices, such as transistors formed inthe substrate 101, to support operation of the memory cells.

In some embodiments, the interconnect structure 105 comprises a lowerinterconnect layer 138 disposed within a lower inter-layer dielectric(ILD) layer 104 and an upper interconnect layer 140 disposed within anupper ILD layer 120. The lower interconnect layer 138 comprises aplurality of lower metal lines having co-planar upper surfaces, such asa first lower metal line 102 at the memory region 124 and a second lowermetal line 103 at the logic region 126 and.

The memory cell 130 comprises a top electrode 136 and a bottom electrode112, which are disposed between the lower interconnect layer 138 and theupper interconnect layer 140. The top and bottom electrodes 136, 112 areseparated by a resistance switching element 134, such as a magnetictunnel junction (MTJ). The bottom electrode 112 is arranged directlyabove the first lower metal line 102, and is electrically coupled to thefirst lower metal line 102 by a narrow, lower portion of the bottomelectrode.

A dummy structure 132 is arranged directly above the second lower metalline 103 at the logic region 126. During manufacturing, the dummystructure 132 acts as a CMP stop over the logic region 126. Thus, forexample, if the dummy structure 132 were not in place, when a CMPoperation was carried out to planarize top surface of bottom electrode112, the CMP operation could cause “dishing” in the logic region 126 andundesirably thin or remove second lower metal line 103. Thus, the dummystructure 132 provides sufficient structural rigidity to resist CMPduring processing to protect the second lower metal line 103 from beingeroded away during manufacturing.

The illustrated dummy structure comprises a dummy bottom electrode 114and a dielectric mask 108 on the dummy bottom electrode 114. In someembodiments where CMP operations on the bottom electrode 112 can beotherwise problematic, the dummy bottom electrode is formed concurrentlywith the bottom electrode 112 and protects against dishing of secondlower metal line 103 due to CMP operations on the bottom electrode 112.In some embodiments, the dielectric mask 108 may comprise siliconcarbide (SiC) and may have a thickness of from about 20 Å to about 200Å.

In some embodiments, a top etch stop layer 116 can extend upwardly alongsidewalls of the dummy structure 132, along sidewalls of the memory cell130, and overlie upper surfaces of the dummy structure 132 and thememory cell 130. The top etch stop layer 116 can also extend over abottom etch stop layer 106, and the top and bottom etch stop layer 116,106 can be made of the same or different dielectric materials. Forexample, the top etch stop layer 116 and the bottom etch stop layer 106can comprise SiC in some embodiments. In some embodiments, a protectiveliner 118 is disposed directly along upper surfaces of the top etch stoplayer 116. The protective liner 118 may comprise TEOS (TetraethylOrthosilicate) material.

In some embodiments, a top electrode via (TEVA) 142 connects a firstupper metal line 122 of the upper interconnect layer 140 and the topelectrode 136 of the memory cell 130. The TEVA 142 is disposed withinthe upper ILD layer 120 through a hole of the top etch stop layer 116and the protective liner 118 and reach the top electrode 136. The topetch stop layer 116 and/or the protective liner 118 continuously coversan upper surface of the dummy structure 132, isolating the dummystructure 132 from the upper ILD layer 120 and the upper interconnectlayer 140. In some embodiments, a through via 144 connects the secondlower metal line 103 to a second upper metal line 128, or other logicdevices.

In some embodiments, the bottom electrode 112 and the dummy bottomelectrode 114 are made of the same material, for example, titaniumnitride (TiN). An upper surface of the dummy bottom electrode 114 of thedummy structure 132 is co-planar with that of the bottom electrode 112of the memory cell 130. A thickness of the dummy bottom electrode 114and the bottom electrode 112 can be the same, and can be about 130 Å insome embodiments. Widths of the dummy bottom electrode 114 and thebottom electrode 112 can be the same or similar in some embodiments, forexample, in a range of from about 200 Å to about 300 Å. In someembodiments, a height of the dummy structure 132 (from a bottom surfaceof the dummy bottom electrode 114 to a top surface of the dummystructure 132) can be about 300 Å smaller than a height of the memorycell (from a bottom surface to the bottom electrode 112 to a top surfaceof the top electrode 136). In some embodiments, the dummy bottomelectrode 114 and the bottom electrode 112 can be respectively coupledto the underlying second lower metal line 103 and first lower metal line102 through a barrier layer 110. In some embodiments, the barrier layer110 comprises tantalum nitride (TaN) and may have a thickness of about10 Å. In some other embodiments, the barrier layer 110 comprisestantalum (Ta) and may have a thickness of about 70 Å. In some otherembodiments, the barrier layer 110 may comprise a conductive oxide,nitride, or oxynitride of a selected metal. In some embodiments, thedummy bottom electrode 114 and the bottom electrode 112 can comprise alower portion, which acts as a bottom electrode via (BEVA) and which isnarrower than an upper portion of the bottom electrode 112. The lowerportion can have tilted sidewalls which are angled in a range of about30° to about 60°, while the upper portion can have vertical or tiltedsidewalls.

FIG. 2 illustrates a cross-sectional view of the memory region 124 ofFIG. 1 including the memory cell 130 according to some embodiments.

As shown in FIG. 2, the interconnect structure 105 can include aplurality of metal layers or other conductive layers (e.g., 140, 138,150, 152, 154) stacked over one another and disposed over the substrate101. Metal lines in the metal layers can be isolated from one another byinterlayer dielectric (ILD) material 104, such as silicon dioxide or alow-K dielectric. For purposes of clarity, logic region 126 is not shownin FIG. 2, but it will be appreciated that interconnect structure 105and substrate 101 also extend under the logic region 126 of FIG. 1 in asimilar manner.

Still referring to FIG. 2, the memory region 124 of the substrate 101has a transistor arranged between isolation regions 203. The transistorincludes a source region 221, a drain region 239, a gate electrode 233,and a gate dielectric 237. A source line 213 (SL) is connected to thesource region 221 through a contact plug 219, a first metal interconnectline 217, and a first metal via 215, which are disposed within one ormore ILD layers 104. A word line (WL) 235 for addressing the memory cell130 is coupled to the gate electrode 233. The bottom electrode 112 ofthe memory cell 130 is connected to the drain region 239 through contactplug 205, first, second, third, and forth metal interconnect layers202A-202D, and metal vias 222A-222C. In this example, the second lowermetal line 202D (e.g., 102 FIG. 1) is located in the fourth metalinterconnect layer, and the upper first upper metal line 122 is locatedin a fifth metal interconnect layer. However, locations of the lowermetal lines 102, 103 and upper metal lines 122, 128 are amenable to anylower or upper metal interconnect layers. In some embodiments, the TEVA142 connects the top electrode 136 of the memory cell 130 to a bit line122 arranged within the fifth metal interconnect layer disposed withinthe upper ILD layer 120. In some embodiments, the memory cell 130 is amagnetoresistive random access memory (MRAM) cell and the resistanceswitching element 134 can comprise a magnetic tunnel junction (MTJ)structure having a bottom ferromagnetic layer and a top ferromagneticlayer separated by a tunnel barrier layer as shown in FIG. 1. In someother embodiments, the memory cell 130 is a resistive random accessmemory (RRAM) cell and the resistance switching element 134 can comprisea RRAM dielectric layer as shown in FIG. 2. The RRAM cell can furthercomprise a hard mask 230 disposed on the top electrode 136 surroundingthe TEVA 142 and a spacer 146 along sidewalls of the resistanceswitching element 134 and the top electrode 136.

FIG. 3 illustrates a flow diagram of a method 300 of manufacturing anintegrated circuit (IC) according to some embodiments.

While disclosed method 300 is illustrated and described below as aseries of acts or events, it will be appreciated that the illustratedordering of such acts or events are not to be interpreted in a limitingsense. For example, some acts may occur in different orders and/orconcurrently with other acts or events apart from those illustratedand/or described herein. In addition, not all illustrated acts may berequired to implement one or more aspects or embodiments of thedescription herein. Further, one or more of the acts depicted herein maybe carried out in one or more separate acts and/or phases.

At act 302, a lower ILD layer is formed over a substrate.

At act 304, a lower interconnect layer is formed within the lower ILDlayer.

At act 306, a bottom etch stop layer is formed over the lower ILD layerand the lower interconnect layer.

At act 308, first and second recesses are formed through the bottom etchstop layer respectively at a memory region and a peripheral region.

At act 310, a barrier layer and a bottom electrode precursor layer areformed in succession over bottom etch stop layer.

At act 312, a bottom electrode planarization is performed.

At act 314, a dielectric mask is formed directly on the bottom electrodeprecursor layer at a position of a dummy bottom electrode to be formed.

At act 316, a resistance switching element and a top electrode areformed on the bottom electrode for a memory cell.

At act 318, the bottom electrode precursor is patterned to form a bottomelectrode for the memory cell at the memory region for the memory celland a dummy bottom electrode for a dummy structure is formed at theperipheral region.

At act 320, a top etch stop layer is formed over the bottom etch stoplayer, along outer sidewalls of the memory cell and dummy structure.

At act 322, an upper ILD layer is formed over the top etch stop layerand a top electrode via and an upper metal line are formed through topetch stop layer to reach on the top electrode.

FIGS. 4-12 illustrate some embodiments of cross-sectional views showinga method of forming an integrated circuit device. Although FIGS. 4-12are described in relation to method 300, it will be appreciated that thestructures disclosed in FIGS. 4-12 are not limited to such a method, butinstead may stand alone as structures independent of the method.

FIG. 4 illustrates some embodiments of a cross-sectional view 400corresponding to acts 302, 304 and 306.

As shown in cross-sectional view 400, corresponding to act 302, a lowerILD layer 104 is formed over a substrate 101. Corresponding to act 304,a lower interconnect layer 138 is formed within the lower ILD layer 104.The lower interconnect layer 138 is formed to have a second lower metalline 103 at a logic region 126 and a first lower metal line 102 at amemory region 124. In some embodiments, the lower interconnect layer 138may be disposed within a back-end-of-the-line (BEOL) metal interconnectstack. The lower metal interconnect layer 402 can comprise lower metalvias or lower metal lines. In some embodiments, the lower interconnectlayer 138 may be formed by selectively etching the lower ILD layer 104(e.g., an oxide, a low-k dielectric, or an ultra low-k dielectric) toform an opening in the lower ILD layer 104. A metal (e.g., copper,aluminum, etc.) is then deposited to fill the opening, and aplanarization process is performed to remove excess metal to form thelower interconnect layer 138.

Corresponding to act 306, a bottom etch stop layer 106 is formed overthe lower ILD layer 104 and the lower interconnect layer 138. In someembodiments, the bottom etch stop layer 106 may comprise silicon-nitride(SiN), silicon-carbide (SiC), or a similar composite dielectric film. Insome embodiments, the bottom etch stop layer 106 may be formed by avapor deposition technique (e.g., physical vapor deposition, chemicalvapor deposition, etc.).

FIG. 5 illustrates some embodiments of a cross-sectional view 500corresponding to act 308.

As shown in cross-sectional view 500, a mask layer 508 is formed overthe bottom etch stop layer 106 to form the first recess 504 and thesecond recess 506. In some embodiments, the mask layer 508 can be anitrogen free anti-reflection layer overlying the bottom etch stoplayer. The mask layer 508 can be a photoresist layer having openingscorresponding to the first and second recesses 504, 506 to be formed. Anetchant 502 is used to remove an exposed portion of the bottom etch stoplayer 106 not covered by the mask layer 508. In some embodiments, thefirst and second recesses 504, 506 can be formed through a dry etchprocess such as a plasma etching. By adjusting powers and flow rate ofreactant gases used in the plasma etching, contours of the first andsecond recesses 504, 506 can be controlled. In some embodiments, atapered or curved sidewall can be formed to facilitate subsequentreliable filling of the first and second recesses 504, 506 with aconductive material. The first recess 504 is formed through the bottometch stop layer 106 at the memory region 124 overlying the first lowermetal line 102 and a second recess 506 is formed through the bottom etchstop layer 106 at the logic region 126 overlying the second lower metalline 103.

FIG. 6 illustrates some embodiments of a cross-sectional view 600corresponding to act 310.

As shown in cross-sectional view 600, the mask layer (508 of FIG. 5) isremoved and a bottom electrode precursor layer 604 is formed within thefirst and second recesses 504, 506 and extending over the bottom etchstop layer 106. A diffusion barrier layer 602 may be deposited on thelower interconnect layer 138 (e.g. the second lower metal line 103 andthe first lower metal line 102) and along the sidewall of the first andsecond recesses 504, 506 prior to deposition of the bottom electrodeprecursor layer 604 to prevent diffusion between the lower interconnectlayer 138 and the bottom electrode precursor layer 604. In variousembodiments, the bottom electrode precursor layer 604 may comprise ametal nitride (e.g., titanium nitride (TiN) or tantalum nitride (TaN) ora metal (e.g., titanium (Ti) or tantalum (Ta)).

FIG. 7 illustrates some embodiments of a cross-sectional view 700corresponding to act 312.

As shown in cross-sectional view 700, the bottom electrode precursorlayer 604 is lowered by a planarization process such aschemical-mechanical polishing to form a planar upper surface 702. Sincea dummy via 704 is formed overlying the second lower metal line 103 atthe logic region 126 similar to a bottom electrode via 706 overlying thefirst lower metal line 102 at the memory region 124, dishing effect tothe second lower metal line 103 is minimized and a thickness of thebottom electrode precursor layer 604 becomes uniform afterplanarization.

FIG. 8 illustrates some embodiments of a cross-sectional view 800corresponding to act 314.

As shown in cross-sectional view 800, a dielectric mask 108 is formeddirectly on the bottom electrode precursor layer 604 overlying a dummyvia 704 at a position of a dummy bottom electrode to be formed. In someembodiments, a mask material is formed over the bottom electrodeprecursor layer 604. Then the mask material is patterned by aphotoresist layer 806. An anti-reflective layer 804 can be formedbetween the photoresist layer 806 and the mask material. In someembodiments, the dielectric mask 108 may be formed by a vapor depositiontechnique (e.g., physical vapor deposition, chemical vapor deposition,etc.). In some embodiments, the dielectric mask 108 may comprisesilicon-nitride (SiN), silicon-carbide (SiC), or a similar compositedielectric film.

FIG. 9 illustrates some embodiments of a cross-sectional view 900corresponding to act 316.

As shown in cross-sectional view 900, a resistance switching element 134and a top electrode 136 are formed in succession over the bottomelectrode precursor layer 604. In some embodiments, a hard mask layerand/or a photoresist layer (not shown) may be subsequently formed on thetop electrode 136 to facilitate the patterning of the memory cell. Insome embodiments, the resistance switching element 134 may comprise aRRAM dielectric layer such as metal oxide composite such as hafniumoxide (HfO_(x)), zirconium oxide (ZrO_(x)), aluminum oxide (AlO_(x)),nickel oxide (NiO_(x)), tantalum oxide (TaO_(x)), or titanium oxide(TiO_(x)) as in its relative high resistance state and a metal such astitanium (Ti), hafnium (Hf), platinum (Pt), ruthenium (Ru), and/oraluminum (Al) as in its relative low resistance state. In someembodiments, the resistance switching element 134 may comprise amagnetic tunnel junction (MTJ) structure having a bottom ferromagneticlayer and a top ferromagnetic layer separated by a tunnel barrier layer.

FIG. 10 illustrates some embodiments of a cross-sectional view 1000corresponding to act 318.

As shown in cross-sectional view 1000, the bottom electrode precursor604 is patterned to form a bottom electrode 112 for a memory cell 130 atthe memory region 124 and a dummy bottom electrode 114 for a dummystructure 132 at the logic region 126. The bottom electrode precursorlayer 604 can be patterned according to the dielectric mask 108 andadditional mask layer overlying the top electrode 136 (not shown). Insome embodiments, the dummy bottom electrode 114 and the bottomelectrode 112 may be patterned by a dry etching process 1002. In someembodiments, the dry etching process 1002 may comprise an etchantchemistry having gases including CF₄, CH₂F₂, Cl₂, BCl₃ and/or otherchemicals.

FIG. 11 illustrates some embodiments of a cross-sectional view 1100corresponding to act 320.

As shown in cross-sectional view 1000, a top etch stop layer 116 isformed over the bottom etch stop layer 106, along outer sidewalls of thememory cell 130 and dummy structure 132. In some embodiments, the topetch stop layer 116 is a conformal dielectric liner made of same ordifferent materials with the bottom etch stop layer 106. The top etchstop layer 116 may comprise silicon-nitride (SiN), silicon-carbide(SiC), or a similar composite dielectric film. In some embodiments, thetop etch stop layer 116 may be formed by a vapor deposition technique(e.g., physical vapor deposition, chemical vapor deposition, etc.). Insome embodiments, a protective liner 118 can be formed along an uppersurface of the top etch stop layer 116. In some embodiments, theprotective liner 118 may comprise silicon nitride, tetraethylorthosilicate (TEOS), silicon-rich oxide (SRO), or a similar compositedielectric film. In some embodiments, the protective liner 118 may beformed by a vapor deposition technique (e.g., physical vapor deposition,chemical vapor deposition, etc.).

FIG. 12 illustrates some embodiments of a cross-sectional view 1200corresponding to act 322.

As shown in cross-sectional view 1200, an upper ILD layer 120 is formedover the top etch stop layer 116 and/or the protective liner 118. Insome embodiments, the upper ILD layer 120 may comprise an oxide layer, alow-k dielectric layer, or an ultra-low-k dielectric layer formed by adeposition process (e.g., CVD, PECVD, PVD, etc.). A top electrode via142 and a first upper metal line 122 are formed through the top etchstop layer 116 and/or the protective liner 118 to reach on the topelectrode 136. A through via 144 and a second upper metal line 128 areformed through the upper ILD layer 120 to reach on the second lowermetal line 103. In some embodiments, the vias and the metal lines may beformed by dual damascene process. Trenches and via holes are formedthrough the upper ILD layer 120, and then filed with a conductivematerial (e.g., copper). A planarization is then performed.

It will be appreciated that while reference is made throughout thisdocument to exemplary structures in discussing aspects of methodologiesdescribed herein that those methodologies are not to be limited by thecorresponding structures presented. Rather, the methodologies (andstructures) are to be considered independent of one another and able tostand alone and be practiced without regard to any of the particularaspects depicted in the Figs. Additionally, layers described herein, canbe formed in any suitable manner, such as with spin on, sputtering,growth and/or deposition techniques, etc.

Also, equivalent alterations and/or modifications may occur to thoseskilled in the art based upon a reading and/or understanding of thespecification and annexed drawings. The disclosure herein includes suchmodifications and alterations and is generally not intended to belimited thereby. For example, although the figures provided herein areillustrated and described to have a particular doping type, it will beappreciated that alternative doping types may be utilized as will beappreciated by one of ordinary skill in the art.

Accordingly, the present disclosure relates to a structure and methodfor forming an integrated circuit having a dummy structure disposed at aperipheral region of the memory region. The dummy structure comprises adummy bottom electrode co-planar with a bottom electrode of a memorycell of the memory region. The dummy structure further comprises adielectric mask disposed on the dummy bottom electrode. The formation ofthe dummy structure provides a sufficient support and etch stopping whenplanarizing the bottom electrode of the memory cell and further helpprovide uniform planarization and eliminate metal line erosion at thelogic region.

In some embodiment, the present disclosure relates to an integratedcircuit (IC) disposed over a substrate. The IC comprises a plurality ofmetal layers disposed within an inter-layer dielectric (ILD) materialover the substrate. The IC further comprises a memory cell disposed overa first metal layer at a memory region and comprising a bottom electrodedirectly above a first metal line within the first metal layer and a topelectrode separated from the bottom electrode by a resistance switchingelement. The IC further comprises a dummy structure comprising a dummybottom electrode arranged directly above a second metal line within thefirst metal layer at a logic region adjacent to the memory region.

In another embodiment, the present disclosure relates to an integratedcircuit (IC). The IC comprises a semiconductor substrate and aninterconnect structure disposed over the semiconductor substrate, theinterconnect structure including a plurality of metal layers disposedover one another and isolated from one another by interlayer dielectric(ILD) material. The IC further comprises a memory cell including a topelectrode and a bottom electrode arranged between a lower metal layerand an upper metal layer of the interconnect structure. The IC furthercomprises a dummy bottom electrode arranged between the lower and uppermetal layers, and having an upper surface that is co-planar with thebottom electrode of the memory cell.

In yet another embodiment, the present disclosure relates to anintegrated circuit (IC). The IC comprises a memory region and a logicregion adjacent to the memory region. A lower metal layer is disposedwithin a lower interlayer dielectric (ILD) layer and an upper metallayer disposed within an upper ILD layer overlying the lower metallayer. A memory cell is arranged within the memory region between thelower metal layer and the upper metal layer. The memory cell comprises atop electrode and a bottom electrode separated by a resistance switchingelement. The bottom electrode is electrically coupled to the lower metallayer and the top electrode is electrically coupled to the upper metallayer. A dummy structure is arranged within the logic region and havinga lower surface aligned with a lower surface of the memory cell. Thedummy structure comprises a dummy bottom electrode and a dummydielectric mask disposed on the dummy bottom electrode

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. An integrated circuit (IC) disposed over asubstrate, comprising: a plurality of metal layers disposed within aninter-layer dielectric (ILD) material over the substrate; a memory celldisposed over a first metal layer at a memory region and comprising abottom electrode directly above a first metal line within the firstmetal layer and a top electrode separated from the bottom electrode by aresistance switching element; and a dummy structure comprising a dummybottom electrode arranged directly above a second metal line within thefirst metal layer at a logic region adjacent to the memory region. 2.The IC of claim 1, wherein the dummy bottom electrode and the bottomelectrode are made of the same material as one another.
 3. The IC ofclaim 1, wherein an upper surface of the dummy bottom electrode isco-planar with an upper surface of the bottom electrode.
 4. The IC ofclaim 1, further comprising: a barrier layer disposed between the dummybottom electrode and the second metal line.
 5. The IC of claim 1,further comprising: a bottom etch stop layer surrounding the bottomelectrode and the dummy bottom electrode; and a top etch stop layerdisposed on the bottom etch stop layer and extending upwardly alongsidewalls of the dummy structure and overlying an upper surface of thedummy structure.
 6. The IC of claim 5, further comprising a dielectricmask disposed on the dummy bottom electrode and covered by the top etchstop layer.
 7. The IC of claim 5, further comprising a TEOS (TetraethylOrthosilicate) liner conformally disposed over the top etch stop layer.8. The IC of claim 1, wherein the memory region comprises a plurality ofresistive random access memory (RRAM) cells respectively comprising abottom electrode and a top electrode separated by a RRAM dielectriclayer.
 9. The IC of claim 1, wherein first metal line is laterallyaligned with the second metal line.
 10. The IC of claim 1, wherein thedummy structure has a width in a range of from about 200 Å to about 300Å.
 11. An integrated circuit (IC), comprising: a semiconductorsubstrate; an interconnect structure disposed over the semiconductorsubstrate, the interconnect structure including a plurality of metallayers disposed over one another and isolated from one another byinterlayer dielectric (ILD) material; a memory cell including a topelectrode and a bottom electrode arranged between a lower metal layerand an upper metal layer of the interconnect structure; and a dummybottom electrode arranged between the lower and upper metal layers, andhaving an upper surface that is co-planar with the bottom electrode ofthe memory cell.
 12. The IC of claim 11, further comprising: adielectric mask disposed over the dummy bottom electrode and havingdummy mask sidewalls aligned to sidewalls of the dummy bottom electrode;and a silicon carbide layer extending upwardly along sidewalls of thedummy bottom electrode, along sidewalls of the dielectric mask, andoverlying an upper surface of the dielectric mask.
 13. The IC of claim12, where the silicon carbide layer extends upwardly along sidewalls ofthe bottom electrode, along sidewalls of the top electrode, and overliesan upper surface of the top electrode.
 14. The IC of claim 11, whereinthe dummy bottom electrode and bottom electrode comprise titaniumnitride (TiN) having a thickness of about 130 Å, and further comprisinga barrier layer disposed between the dummy bottom electrode and anunderlying metal line comprising tantalum nitride (TaN) with a thicknessof about 10 Å.
 15. The IC of claim 11, further comprising a barrierlayer disposed between the dummy bottom electrode and an underlyingmetal line and comprising tantalum (Ta) with a thickness of about 70 Å.16. An integrated circuit (IC), comprising: a memory region and a logicregion adjacent to the memory region; a lower metal layer disposedwithin a lower interlayer dielectric (ILD) layer and an upper metallayer disposed within an upper ILD layer overlying the lower metallayer; a memory cell arranged within the memory region between the lowermetal layer and the upper metal layer, the memory cell comprising a topelectrode and a bottom electrode separated by a resistance switchingelement, wherein the bottom electrode is electrically coupled to thelower metal layer and the top electrode is electrically coupled to theupper metal layer; and a dummy structure arranged within the logicregion and having a lower surface aligned with a lower surface of thememory cell, the dummy structure comprising a dummy bottom electrode anda dummy dielectric mask disposed on the dummy bottom electrode.
 17. TheIC of claim 16, wherein the dummy dielectric mask has a sidewall alignedwith a sidewall of the dummy bottom electrode.
 18. The IC of claim 16,further comprising: a top etch stop layer disposed over the lower ILDlayer, extending upwardly along sidewalls of the memory cell and thedummy structure, and overlying surfaces of the memory cell and the dummystructure.
 19. The IC of claim 18, wherein the top etch stop layercontacts and covers a top surface of the dummy dielectric mask.
 20. TheIC of claim 16, wherein the dummy bottom electrode is coupled to a lowermetal line of the lower metal layer, wherein the lower metal line isconnected to an upper metal line of the upper metal layer through aconductive via.